vics_si

Hey guys, I got a problem with my 99 Civic Si, when it warms up up the idle bounces from about 1 grand to 2400. It's fine when it's cold, you can drive it around untill it warms up, then it idles funny and then throws a code, I can keep it from throwing the code by holding out the clutch while stopped and keeping the idle on 1 grand, but if I dont when it idles funny it throws the check engine light on. I dont hasve anything to read the code with, so yeah.
I just replaced the IAC and it didn't fix it. I just installed a new intake manifold that didn't work, it made the car idle way high, so I took that off and put my AEM fuel rail on, which did work. Everything else stock but the fuel rail. If you need any info about the car, let me know.

By the way, it's a B16A2.